Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

High-consequence terrain at upper elevations may harbor old or newly formed wind deposits which, although shallow, could avalanche with a human trigger and take you for a dangerous ride. Think twice before entering steep terrain at upper elevations if there are trees, cliffs, or other hazardous features on the slopes beneath you. Avoid the slope if you notice newly drifted snow or old deposits that exhibit signs of weakness, such as long shooting cracks. 

 

 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Wind-drifted pockets up high, even if small, could cause harm if you're in steep, exposed, high-consequence terrain. Many areas you travel could have low danger. However, we've got uncertainty at upper elevations and enough of a concern to not quite put us into green all around. 

    Wind speeds are strong enough that newly formed shallow drifts may build on Tuesday. These recently formed deposits are where you're most likely to trigger an avalanche. They may only be noticeable once you transition over a onto a new aspect, albeit subtle. Pause before you head onto a steep slope with dangerous terrain traps below you. Consider avoiding these steep, high-consequence features if you identify thicker wind deposits, and especially if there are any red flags such as long, shooting cracks from your feet or sled. 

    (1/27/2023)

    Example photo: Small wind slab avalanches in high consequence terrain on the east-facing aspect of Video Peak in the Baker backcountry from last year.  Note the textured, wind-affected surfaces on the lower-angle terrain above. indicating areas of wind loading. These sort of areas, with cliffs, trees, and gullies are places you should probably avoid on Tuesday. 

    Photo: Jason Speer - The Mountaineers

Avalanche Discussion

In the last few days,there have been a few large large natural avalanches that occurred on distant peaks at higher elevations. They may have failed above the 12/30 crust, and most are a few days old. An observer today scanned far and wide, trying to find more than the single one they identified on a steep, unsupported slope, with views of many surrounding peaks and didn't see any others.  We suspect the locations where these occurred are isolated and on large, unsupported upper-elevation slopes. This weak layer is around 3 or more feet deep, so we believe it would be very difficult for a human to trigger an avalanche on this layer. This doesn't warrant enough of an alarm bell to put this concern in as an avalanche problem at this time. We'll have to wait and see what happens when we get more snow. 

Regarding Tuesday night's incoming snow, an observer reported finding an abundance of faceted, weak snow layers at or near the surface due to our recent cold temperatures. This was especially the case in wind-scoured spots where the crust that formed mid-storm on 1/8  is nearer to the surface. Overall, reports are coming in that wind-affected surfaces are abundant, yet low-density snow still exists in many areas. On Sunday, I found a thin layer of near-surface facets on steep, south-facing aspects sneakily hiding above the newly formed surface crust.   

We've got quite a patchwork of snow surfaces that will react in different ways with added snow, something to keep in mind when more snow is added. Backcountry users are still reporting thinner snowpacks at lower elevations, where trees, rocks, and possibly frozen-over creeks are still exposed or just barely hidden. 

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